Mosquitoes are known carriers of many diseases globally including West Nile Virus. Currently, West Nile Virus is causing some concerns in the USA.
Because mosquitoes are aquatic in their immature stages, they must have water in which to develop. The larvae cannot develop in tall grass or shrubbery. Although the adults may be found resting in these spots during the day.
Hence, the source reduction is a preferable approach for mosquito control. When water that produces mosquitoes can be removed without causing other problems. Similarly, landscape planning that keeps water from accumulating is always a good bet.